Multifunctional coating films of gelatin/d-glucose/agarose reinforced by Piper L. leaf extract: Physicochemical properties and mandarin preservation

Eco-friendly, active, non-toxic coatings have recently been considered as a feasible approach for enhancing the storability of post-harvest produce, which deal with global problem from environmental pollutions of chemical uses and petro-based plastics. In this interest, the present work is to the development of multifunctional coating films through blending gelatin, agarose, d-glucose, and Piper betle L. extract before being applied for preserving 'Duong' mandarin. As compared to single addition of agarose, the co-supplement of agarose and d-glucose was considered to be more efficient in revitalizing the mechanical strength and surface hydrophobicity of the neat gelatin, which highlighted a vital role of d-glucose in the polymeric network. Interestingly, gelatin/d-glucose/agarose formulated with Piper betle L. extract showed greater mechanical strength, flexibility, UV-shielding, solubility, antibacterial and antioxidant activities than gelatin/d-glucose/agarose coating films. Considerably, the antibacterial property of such active films/coatings was found to even better after being aged for 30 days at the room temperature (25 °C). Based on initial screening, the gelatin/agarose/d-glucose coating formulation included with 2 % (w/w) Piper betle L. extract presenting the best mechanical strength (2.46 MPa), flexibility (31.03 %), and antioxidant activity (IC50 = 37.45 μg/mL) along with the adequate tested bacterial inhibition, was applied for ready-to-eat mandarin preservation. The significant improvement in visual appearance and peel color was recorded for the mandarin coated with gelatin/agarose/d-glucose/Piper betle L. extract (2 %, w/w) after 17-d storage at 20 °C and 64 %RH, which exhibited the lowest mass loss and total soluble solids.